Ejector

ABSTRACT

A swirling space in which a refrigerant is swirled into a gas-liquid mixing state includes an upstream swirling space in which the refrigerant flowing from an external is swirled, and a downstream swirling space in which the refrigerant flowing from the upstream swirling space is introduced into a nozzle passage while swirling. Further, a cross-sectional shape of an outlet part of the upstream swirling space is formed into an annular shape along an outer peripheral shape of the upstream swirling space.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by referenceJapanese Patent Application No. 2013-103141 filed on May 15, 2013.

TECHNICAL FIELD

The present disclosure relates to an ejector that depressurizes a fluid,and draws the fluid by a suction action of an ejection fluid at highspeed.

BACKGROUND ART

Up to now, Patent Document 1 discloses a depressurizing device that isapplied to a vapor compression refrigeration cycle device, anddepressurizes the refrigerant.

The depressurizing device of Patent Document 1 has a main body thatdefines a swirling space in which the refrigerant is swirled, and swirlsthe refrigerant within the swirling space, to thereby reduce arefrigerant pressure on a swirling center side to a pressure at whichthe refrigerant is depressurized and boiled (cavitation occurs).Further, the depressurizing device allows the refrigerant in agas-liquid mixing state in which a gas-phase refrigerant and aliquid-phase refrigerant on the swirling center side are mixed togetherto flow into a minimum passage area part for depressurization.

With the above configuration, in the depressurizing device of PatentDocument 1, even if a state of the refrigerant flowing into the swirlingspace changes due to a change in an outside temperature, a density ofthe refrigerant flowing into the minimum passage area part is restrainedfrom largely changing to suppress a variation in a flow rate of therefrigerant flowing toward a downstream side of the depressurizingdevice.

Patent Document 1 also discloses an ejector using the depressurizingdevice as a nozzle. The ejector of this type draws the gas-phaserefrigerant flowing out of the evaporator due to the suction action ofthe ejected refrigerant ejected from the nozzle, and mixes the ejectedrefrigerant with the suction refrigerant in a pressure increase part(diffuser portion), thereby being capable of increasing the pressure.

Accordingly, in a refrigeration cycle device (hereinafter referred to asan ejector type refrigeration cycle) including an ejector as arefrigerant depressurization device, power consumption of a compressorcan be reduced with the use of a refrigerant pressure increase action inthe pressure increase part of an ejector, and a coefficient ofperformance (COP) of a cycle can be improved to a greater extent than ageneral refrigeration cycle device including an expansion valve or thelike as the refrigerant depressurization device.

Further, in the ejector disclosed in Patent Document 1, as describedabove, a variation in the ejected refrigerant ejected from the nozzle issuppressed, and the refrigerant in the gas-liquid mixing state isdepressurized in the minimum passage area part to promote the boiling ofthe liquid-phase refrigerant and improve the nozzle efficiency. Thenozzle efficiency represents an energy conversion efficiency forconverting a pressure energy of the refrigerant into a kinetic energy inthe nozzle.

However, in the ejector disclosed in Patent Document 1, when the stateof the refrigerant flowing into the swirling space changes due to thechange in the outside temperature, the variation in the flow rate of theejected refrigerant ejected from the nozzle can be suppressed. However,there is a case in which the nozzle efficiency cannot be improved to adesired value depending on an operation condition.

Under the circumstances, the present inventors have searched the cause,and found that in the ejector disclosed in Patent Document 1, therefrigerant flows into a tangential direction of the swirling spacecircular in cross-section when the refrigerant flows into the swirlingspace, and this flow makes impossible to improve the nozzle efficiencyto the desired value. The reason is because when the refrigerant flowsin the tangential direction of the swirling space circular incross-section, the depressurization and boiling of the refrigerant inthe swirling space is limited as will be described later.

When the depressurization and boiling of the refrigerant within theswirling space is limited, a ratio of the gas-phase refrigerant to therefrigerant in the gas-liquid mixing state which flows into the minimumpassage area part decreases to reduce boiling nucleus for promoting theboiling of the liquid-phase refrigerant, resulting in a boiling delay ofpartial liquid-phase refrigerant. As a result, the refrigerant ejectedfrom the minimum passage area part cannot be effectively accelerated,which may cause the nozzle efficiency to be reduced.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: JP 2012-202653 A

SUMMARY OF THE INVENTION

In view of the above, it is an objective of the present disclosure is tolimit a reduction in nozzle efficiency of an ejector that depressurizesa fluid which is swirled into a gas-liquid mixing state.

According to a first aspect of the present disclosure, an ejectorincludes a swirling space formation member having a swirling space inwhich a fluid is swirled, a nozzle that depressurizes and ejects thefluid flowing out of the swirling space, and a body including a fluidsuction port that draws a fluid due to a suction action of the ejectedfluid at high speed which is ejected from the nozzle, and a pressureincrease part that mixes the ejected fluid with the suction fluid drawnfrom the fluid suction port and increases a pressure of the mixed fluid.The swirling space includes an upstream swirling space in which thefluid flowing from an external is swirled, and a downstream swirlingspace that introduces the fluid flowing out of the upstream swirlingspace into the nozzle with keeping the fluid swirling. The upstreamswirling space and the downstream swirling space have respectiverotating body shapes in which center axes are disposed coaxially witheach other. The upstream swirling space has an outlet part through whichthe fluid outflows to the downstream swirling space, and the outlet parthas an annular shape along an outer peripheral shape of the upstreamswirling space in a cross sectional surface perpendicular to the centeraxis. The downstream swirling space has a circular shape in a crosssectional surface perpendicular to the center axis.

According to the above configuration, the fluid swirls in an upstreamswirling space and a downstream swirling space with the result that afluid pressure in the downstream swirling space on the swirling centerside can be reduced to a pressure at which the fluid is depressurizedand boiled (cavitation is generated). Further, the fluid in thegas-liquid mixing state where the gas-phase fluid and the liquid-phasefluid in the downstream swirling space on the swirling center side aremixed together is allowed to flow into the nozzle, and can bedepressurized. The refrigerant in the gas-liquid mixing state does notmean only the refrigerant in a gas-liquid two-phase state, but includesthe refrigerant in a state in which air bubbles are mixed in therefrigerant in a subcooled liquid-phase state.

Further, since a cross-sectional space of an outlet part is formed intoan annular shape along an outer peripheral shape of the upstreamswirling space, the fluid flowing out of the upstream swirling space canflow from an outer peripheral side of the downstream swirling space inan axial direction.

With the above configuration, the fluid flowing out of the upstreamswirling space can be restrained from flowing toward the swirling centerside of the downstream swirling space which has a hollow rotating bodyshape. In addition, the fluid flowing out of the upstream swirling spacecan merge into a flow of the liquid-phase fluid staying and circulatingin the downstream swirling space from the outer peripheral side towardthe nozzle.

Therefore, the flow of fluid staying and circulating in the downstreamswirling space is not blocked by the fluid flowing from the upstreamswirling space into the downstream swirling space, and the ratio of thegas-phase fluid to the fluid in the gas-liquid mixing state flowing intothe nozzle can be restrained from being lowered.

As a result, the boiling of the liquid-phase fluid in the nozzle can bepromoted, and a reduction in the nozzle efficiency of the ejector can belimited.

According to a second aspect of the present disclosure, an ejector isused for a vapor compression refrigeration cycle device. The ejectorincludes a body including a refrigerant inlet port, a swirling space inwhich a refrigerant flowing from the refrigerant inlet port is swirled,a depressurizing space in which the refrigerant flowing out of theswirling space is depressurized, a suction passage that communicateswith a downstream side of the depressurizing space in a refrigerant flowand draws a refrigerant from an external, and a pressurizing space inwhich an ejection refrigerant ejected from the depressurizing space ismixed with a suction refrigerant drawn from the suction passage. Theejector further includes a passage formation member that includes atleast a portion disposed inside the depressurizing space, and a portiondisposed inside the pressurizing space, and the passage formation memberhas a conical shape which increases in cross-sectional area in adirection away from the depressurizing space. A refrigerant passageprovided between an inner peripheral surface of the body defining thedepressurizing space and an outer peripheral surface of the passageformation member is a nozzle passage functioning as a nozzle thatdepressurizes and ejects the refrigerant flowing out of the swirlingspace. A refrigerant passage provided between an inner peripheralsurface of the body defining the pressurizing space and an outerperipheral surface of the passage formation member is a diffuser passagefunctioning as a diffuser that mixes and pressurizes the ejectionrefrigerant and the suction refrigerant. The swirling space includes anupstream swirling space in which the refrigerant flowing from anexternal is swirled, and a downstream swirling space in which therefrigerant flowing out of the upstream swirling space is introducedinto the nozzle passage with swirling. The upstream swirling space andthe downstream swirling space have respective rotating body shapes inwhich center axes are disposed coaxially with each other. The upstreamswirling space has an outlet part through which the refrigerant outflowto the downstream swirling space, and the outlet part has an annularshape along an outer peripheral shape of the upstream swirling space ina cross sectional surface perpendicular to the center axis. Thedownstream swirling space has a circular shape in a cross sectionalsurface perpendicular to the center axis.

According to the above configuration, as in the above first aspect, therefrigerant in the gas-liquid mixing state where the gas-phaserefrigerant and the liquid-phase refrigerant in the downstream swirlingspace on the swirling center side are mixed together is allowed to flowinto the nozzle passage, and can be depressurized. Further, therefrigerant flowing out of the upstream swirling space can merge intothe flow of the liquid-phase refrigerant staying and circulating in thedownstream swirling space from the outer peripheral side toward thenozzle passage.

Therefore, the flow of refrigerant staying and circulating in thedownstream swirling space is not blocked by the refrigerant flowing fromthe upstream swirling space into the downstream swirling space, and theratio of the gas-phase refrigerant to the refrigerant in the gas-liquidmixing state flowing into the nozzle passage can be restrained frombeing lowered.

As a result, boiling of the liquid-phase refrigerant in the nozzlepassage can be promoted, and a reduction in energy conversion efficiency(corresponding to the nozzle efficiency) when the pressure energy of therefrigerant is converted into a velocity energy can be limited in thenozzle passage of the ejector.

The passage formation member is not strictly limited to one having onlythe shape in which the sectional area increases with distance from thedepressurizing space. At least a part of the passage formation membermay include a shape in which the sectional area expands with distancefrom the depressurizing space whereby the diffuser passage has a shapeexpanding outward with distance from the depressurizing space.

Further, “formed into a conical shape” is not limited to a meaning thatthe passage formation member is formed into a complete conical shape,but includes a shape similar to a cone, a shape partially including theconical shape, or a shape combining the conical shape, a cylindricalshape, or a truncated conical shape. Specifically, a sectional shape inan axial direction is not limited to an isosceles triangle, and mayinclude a shape that has two sides in a state where an apex isinterposed between two sides that are convex toward the innercircumferential side, a shape that has two sides in a state where anapex is interposed between two sides that are convex toward the outerperipheral side, a shape in which the sectional shape is formed in asemicircular shape, or the like.

The “rotating body shape” means a solid shape formed by rotating a planefigure around one straight line (center axis) extending on the sameplane.

Further, “annular shape” along the outer peripheral shape of theupstream swirling space does not mean only a “complete annular shape”,but means a shape that is formed into a “substantially annular shape”even if the outlet part is divided by a connection part of a memberforming the outlet part. Therefore, the annular shape may be configuredby combination of two semicircular shapes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an ejector refrigeration cycleaccording to a first embodiment of the present disclosure.

FIG. 2 is a cross-sectional view along an axis direction of an ejectoraccording to the first embodiment.

FIG. 3 is a schematic cross-sectional view illustrating a function ofeach refrigerant passage of the ejector of the first embodiment.

FIG. 4 is a cross-sectional view taken along a line IV-IV in FIG. 3.

FIG. 5 is a Mollier diagram illustrating a state of a refrigerant in theejector refrigeration cycle according to the first embodiment.

FIG. 6 is a cross-sectional view along an axial direction of an ejectoraccording to a second embodiment of the present disclosure.

FIG. 7 is a schematic cross-sectional view illustrating a function ofeach refrigerant passage of the ejector of the second embodiment.

FIG. 8 is a cross-sectional view taken along a line VIII-VIII of FIG. 6.

FIG. 9 is a schematic view illustrating an ejector refrigeration cycleaccording to a third embodiment of the present disclosure.

FIG. 10 is a cross-sectional view along an axis direction of an ejectoraccording to the third embodiment.

FIG. 11 is a schematic cross-sectional view illustrating a flow of arefrigerant within a swirling space of a depressurizing device inresults of simulation analysis by the present inventors.

EMBODIMENTS FOR EXPLOITATION OF THE INVENTION

Hereinafter, multiple embodiments for implementing the present inventionwill be described referring to drawings. In the respective embodiments,a part that corresponds to a matter described in a preceding embodimentmay be assigned the same reference numeral, and redundant explanationfor the part may be omitted. When only a part of a configuration isdescribed in an embodiment, another preceding embodiment may be appliedto the other parts of the configuration. The parts may be combined evenif it is not explicitly described that the parts can be combined. Theembodiments may be partially combined even if it is not explicitlydescribed that the embodiments can be combined, provided there is noharm in the combination.

First Embodiment

A first embodiment of the present disclosure will be described withreference to FIGS. 1 to 5. As illustrated in an overall configurationdiagram of FIG. 1, an ejector 13 according to this embodiment is appliedto a refrigeration cycle device having an ejector as a refrigerantdepressurizing device, that is, an ejector refrigeration cycle 10.Moreover, the ejector refrigeration cycle 10 is applied to a vehicle airconditioning apparatus, and performs a function of cooling a blast airwhich is blown into a vehicle interior that is a space to beair-conditioned.

In addition, an HFC-based refrigerant (more specifically, R134a) isapplied as the refrigerant in the ejector refrigeration cycle 10, and avapor compression type subcritical refrigeration cycle in which highpressure-side refrigerant pressure does not exceed critical pressure ofthe refrigerant is configured. It is needless to say that an HFO-basedrefrigerant (for example, R1234yf) may be employed as the refrigerant.Furthermore, refrigerator oil for lubricating a compressor 11 is mixedin the refrigerant, and a part of the refrigerator oil circulates in thecycle together with the refrigerant.

In the ejector type refrigeration cycle 10, the compressor 11 draws therefrigerant, increases the pressure of the refrigerant until therefrigerant becomes a high-pressure refrigerant, and discharges thepressurized refrigerant. Specifically, the compressor 11 of thisembodiment is an electric compressor that is configured to accommodate afixed capacity type compression mechanism 11 a and an electric motor 11b for driving the compression mechanism 11 a in a single housing.

As the compression mechanism 11 a, various compression mechanisms suchas a scroll compression mechanism or a vane compression mechanism arecapable of being adopted. The electric motor 11 b controls an operation(rotation speed) of the electric motor according to control signalsoutput from a control device to be described below, and any motor of anAC motor and a DC motor may be applied.

The compressor 11 may be an engine driven compressor that is driven by arotation driving force transmitted via a pulley, a belt, or the likefrom a vehicle travel engine. As the engine driven compressor of thistype, a variable capacity compressor that can adjust a refrigerantdischarge capacity by a change in discharge capacity, or a fixedcapacity type compressor that adjusts the refrigerant dischargingcapacity by changing an operation rate of the compressor throughconnection/disconnection of an electromagnetic clutch can be applied.

A refrigerant inlet side of a condenser 12 a of a radiator 12 isconnected to a discharge port side of the compressor 11. The radiator 12is a radiation heat exchanger which performs heat exchange between ahigh pressure refrigerant discharged from the compressor 11 and avehicle exterior air (outside air) blown by a cooling fan 12 d toradiate the heat of the high pressure refrigerant for cooling.

More specifically, the heat radiator 12 is a so-called subcoolingcondenser including: the condenser 12 a, a receiver part 12 b, and asubcooling portion 12 c. The condenser 12 a performs heat exchangebetween the high pressure gas-phase refrigerant discharged from thecompressor 11 and the outside air blown from the cooling fan 12 d, andradiates the heat of the high pressure gas-phase refrigerant to condensethe refrigerant. The receiver part 12 b separates gas and liquid of therefrigerant flowing out of the condenser 12 a and stores a surplusliquid-phase refrigerant. The subcooling portion 12 c performs heatexchange between the liquid-phase refrigerant flowing out of thereceiver part 12 b and the outside air blown from the cooling fan 12 dto subcool the liquid-phase refrigerant.

The cooling fan 12 d is an electric blower of which the rotating speed(the amount of blast air) is controlled by a control voltage output fromthe control device. A refrigerant inlet port 31 a of the ejector 13 isconnected to a refrigerant outlet side of the subcooling portion 12 c ofthe heat radiator 12.

The ejector 13 functions as a refrigerant depressurizing device fordepressurizing the high pressure liquid-phase refrigerant (fluid) of thesubcooling state, which flows out of the heat radiator 12, and allowingthe refrigerant to flow out to the downstream side. The ejector 13 alsofunctions as a refrigerant circulating device (refrigerant transportdevice) for drawing (transporting) the refrigerant (fluid) flowing outof an evaporator 14 to be described later by the suction action of therefrigerant (fluid) ejected at high speed to circulate the refrigerant.Further, the ejector 13 according to this embodiment also functions as agas-liquid separation device for separating the depressurizedrefrigerant into gas and liquid.

A specific configuration of the ejector 13 will be described withreference to FIGS. 2 to 4. Meanwhile, up and down arrows in FIG. 2indicate, respectively, up and down directions in a state where theejector refrigeration cycle 10 is mounted on a vehicle air conditioningapparatus. Also, FIGS. 3 and 4 are schematic cross-sectional viewsillustrating functions and shapes of the respective refrigerant passagesof the ejector 13, and the same parts as those in FIG. 2 are denoted byidentical symbols.

First, as illustrated in FIG. 2, the ejector 13 according to thisembodiment includes a body 30 configured by the combination of pluralcomponents. Specifically, the body 30 has a housing body 31 made ofprismatic-cylindrical or circular-cylindrical metal or resin, andforming an outer shell of the ejector 13. A nozzle body 32, a middlebody 33, and a lower body 34 are fixed to an interior of the housingbody 31.

The housing body 31 is formed with a refrigerant inlet port 31 a, arefrigerant suction port 31 b, a liquid-phase refrigerant outlet port 31c, and a gas-phase refrigerant outlet port 31 d. The refrigerant inletport 31 a allows the refrigerant flowed out of the heat radiator 12 toflow into the body 30. The refrigerant suction port 31 b is configuredto draw the refrigerant flowing out of the evaporator 14. Theliquid-phase refrigerant outlet port 31 c allows a liquid-phaserefrigerant separated by a gas-liquid separation space 30 f formedwithin the body 30 to flow out to the refrigerant inlet side of theevaporator 14. The gas-phase refrigerant outlet port 31 d allows thegas-phase refrigerant separated by the gas-liquid separation space 30 fto flow out to the intake side of the compressor 11.

The refrigerant inlet port 31 a is opened in the center of an uppersurface of the housing body 31. Further, a refrigerant inflow passage 31e for introducing the refrigerant into the interior of the body 30 fromthe refrigerant inlet port 31 a is formed into a cylindrical shapehaving a center axis extended in a vertical direction (verticaldirection in FIG. 2). Further, the refrigerant inflow passage 31 eintroduces the refrigerant flowing from the refrigerant inlet port 31 ainto a space formed within the nozzle body 32. In FIGS. 2 and 3, thecenter axis of the refrigerant inflow passage 31 e is indicated by adashed line.

The nozzle body 32 is formed of a substantially conical metal membertapered toward a refrigerant flow direction, and a part of a swirlingspace 30 a for swirling the refrigerant and a depressurizing space 30 bfor depressurizing the refrigerant flowing out of the swirling space 30a are defined in the interior of the nozzle body 32. The part of theswirling space 30 a and the depressurizing space 30 b are formed into arotating body shape by combination of a cylindrical shape and atruncated conical shape.

Further, the nozzle body 32 is fixed to the interior of the housing body31 by press fitting so that the center axis of the space defined in theinterior of the nozzle body 32 is disposed coaxially with the centeraxis of the refrigerant inflow passage 31 e.

A swirling promotion member 38 that swirls the refrigerant flowing fromthe refrigerant inlet port 31 a around the center axis of therefrigerant inflow passage 31 e is fixed in the interior of therefrigerant inflow passage 31 e. The swirling promotion member 38includes an upper plate 38 a and a lower plate 38 b which are eachformed into a disc shape, and whose plate surfaces are disposed inparallel to each other, and multiple flow regulating plates 38 cdisposed between those plates 38 a and 38 b.

The upper plate 38 a forms a fixing portion for fixing the swirlingpromotion member 38 to the interior of the refrigerant inflow passage 31e. Specifically, an outer peripheral side surface of the upper plate 38a is press-fitted into an inner peripheral wall surface of therefrigerant inflow passage 31 e. A through-hole that penetrates throughfront and rear sides of the upper plate 38 a is defined in the center ofthe upper plate 38 a, and the through-hole configures an inlet part 38 dfor allowing the refrigerant flowing from the refrigerant inlet port 31a to flow toward the nozzle body 32 side.

As illustrated in FIG. 4, an outer diameter of the lower plate 38 b isformed to be smaller than an inner diameter of the refrigerant inflowpassage 31 e. Therefore, a gap formed into an annular shape when viewedfrom the axial direction of the refrigerant inflow passage 31 e isdefined between an outer peripheral side of the lower plate 38 b and aninner peripheral wall surface of the refrigerant inflow passage 31 e.The annular gap configures an outlet part 38 e for allowing therefrigerant flowing into the space between the upper plate 38 a and thelower plate 38 b to flow toward the nozzle body 32 side. No through-holeis defined in the lower plate 38 b.

As illustrated in FIG. 4, the multiple flow regulating plates 38 c arearranged in an annular shape around the center axis of the refrigerantinflow passage 31 e. Further, the plate surfaces of the respective flowregulating plates 38 c are so tilted or curved as to swirl a flow of therefrigerant around the center axis when viewed from the center axisdirection.

Therefore, the refrigerant flowing into the refrigerant inflow passage31 e from the refrigerant inlet port 31 a flows into the space betweenthe upper plate 38 a and the lower plate 38 b through the inlet part 38d of the upper plate 38 a. The refrigerant flowing into the spacebetween the upper plate 38 a and the lower plate 38 b flows from thecenter axis radially outward within the space. In this situation, therefrigerant flows along the plate surfaces of the flow regulating plates38 c whereby the refrigerant swirls around the center axis.

The refrigerant that reaches an outer peripheral side of the spacebetween the upper plate 38 a and the lower plate 38 b flows into a spacebelow (downstream of) the lower plate 38 b from the outlet part 38 eformed in the outer peripheral side of the lower plate 38 b whileswirling around the center axis. Further, the refrigerant that flowsinto the space below (downstream of) the lower plate 38 b is introducedinto a nozzle passage 13 a side to be described later while swirlingaround the center axis.

As is apparent from the above description, as illustrated in FIG. 3, theswirling promotion member 38 according to this embodiment (specifically,the upper plate 38 a) partitions the swirling space 30 a below(downstream of) the swirling promotion member 38. Further, the spacedefined between the upper plate 38 a and the lower plate 38 b in theinterior of the swirling promotion member 38 is an example of anupstream swirling space 301 in which the refrigerant flowing from anexternal swirls.

The outlet part 38 e for allowing the refrigerant to flow out of thespace (upstream swirling space 301) defined between the upper plate 38 aand the lower plate 38 b is formed into the inner peripheral shape ofthe refrigerant inflow passage 31 e in a cross-sectional surfaceperpendicular to the axial direction of the upstream swirling space 301,that is, an annular shape along the outer peripheral shape of theupstream swirling space 301.

Further, the swirling space 30 a below (downstream of) the lower plate38 b is an example of a downstream swirling space 302 for introducingthe refrigerant flowing out of the upstream swirling space 301 towardthe depressurizing space 30 b side while swirling.

In this example, the swirling space 30 a (downstream swirling space 302)below the lower plate 38 b is formed into a hollow rotating body shape,that is, a circular shape in a cross-sectional surface perpendicular tothe axial direction of the refrigerant inflow passage 31 e. Therefore,in the downstream swirling space 302, a refrigerant pressure on thecenter axis side is reduced more than the refrigerant pressure on theouter peripheral side due to the action of a centrifugal force generatedby swirling the refrigerant.

Under the circumstances, in this embodiment, at the time of a normaloperation of the ejector refrigeration cycle 10, the refrigerantpressure on the center axis side in the downstream swirling space 302decreases down to a pressure at which the refrigerant is depressurizedand boiled (cavitation is generated). The refrigerant pressure on thecenter axis side within the downstream swirling space 302 as describedabove can be adjusted by adjustment of the number or the tilt angle offlow regulating plates 38 c, or by adjustment of the layout of the flowregulating plates 38 c (for example, speed increasing cascadearrangement).

The depressurizing space 30 b is defined below the swirling space 30 a(specifically, downstream swirling space 302) in the space defined inthe nozzle body 32. The depressurizing space 30 b is formed into arotating body into which the cylindrical space is coupled with atruncated conical space that gradually spreads toward the refrigerantflow direction continuously from a lower side of the cylindrical space.

Further, a passage formation member 35 is disposed in the interior ofthe depressurizing space 30 b. The passage formation member 35 forms aminimum passage area part 30 m smallest in the refrigerant passage areawithin the depressurizing space 30 b, and changes the passage area ofthe minimum passage area part 30 m. The passage formation member 35 isformed in an approximately conical shape which gradually spreads towarda downstream side in a refrigerant flow, and a center axis of thepassage formation member 35 is disposed coaxially with the center axisof the refrigerant inflow passage 31 e. In other words, the passageformation member 35 is formed into a conical shape having across-sectional area increased with distance from the depressurizingspace 30 b.

The refrigerant passage is formed between an inner peripheral surface ofa portion of the nozzle body 32 which defines the depressurizing space30 b and an outer peripheral surface of the upper side of the passageformation member 35. As illustrated in FIG. 3, the refrigerant passageincludes a convergent part 131 and a divergent part 132. The convergentpart 131 is formed on the upstream side of the minimum passage area part30 m in the refrigerant flow, in which the refrigerant passage areaextending to the minimum passage area part 30 m gradually decreases. Thedivergent part 132 is formed on the downstream side of the minimumpassage area part 30 m in the refrigerant flow, in which the refrigerantpassage area gradually increases.

In the convergent part 131 and the divergent part 132, since thedepressurizing space 30 b overlaps with the passage formation member 35when viewed from the radial direction, a sectional shape of therefrigerant passage perpendicular to the axis direction is annular(doughnut shape obtained by removing a smaller-diameter circular shapearranged coaxially from the circular shape). Further, since a spreadangle of the passage formation member 35 of this embodiment is smallerthan a spread angle of the circular truncated conical space of thedepressurizing space 30 b, the refrigerant passage area of the divergentpart 132 gradually enlarges toward the downstream side in therefrigerant flow.

In this embodiment, the refrigerant passage defined between the innerperipheral surface of the depressurizing space 30 b and the outerperipheral surface of a top side of the passage formation member 35 is anozzle passage 13 a that functions as a nozzle by the passage shape. Inthe nozzle passage 13 a, the refrigerant is depressurized, andaccelerated and ejected in a state where a flow rate of the refrigerantin the gas-liquid mixing state becomes higher than a two-phase soundvelocity.

Since the refrigerant flowing into the nozzle passage 13 a swirls in theswirling space 30 a (specifically, downstream swirling space 302), therefrigerant flowing through the nozzle passage 13 a, and the ejectedrefrigerant that is ejected from the nozzle passage 13 a also have avelocity component in a direction of swirling in the same direction asthat of the refrigerant swirling in the swirling space 30 a (upstreamswirling space 301 and downstream swirling space 302).

Next, as illustrated in FIG. 2, the middle body 33 is formed of adisc-shaped member made of metal which defines a through-hole of therotating body shape which penetrates through both sides thereof in thecenter of the middle body 33. The middle body 33 accommodates a drivingdevice 37 on an outer peripheral side of the through-hole, and thedriving device 37 displaces the passage formation member 35. Meanwhile,a center axis of the through-hole is arranged coaxially with the centeraxes of the refrigerant inflow passage 31 e and the passage formationmember 35. The middle body 33 is fixed to the interior of the housingbody 31 and the lower side of the nozzle body 32 by press fitting.

An inflow space 30 c is provided between an upper surface of the middlebody 33 and an inner wall surface of the housing body 31 facing themiddle body 33, and the inflow space 30 c accumulates the refrigerantflowing from the refrigerant suction port 31 b. Meanwhile, in thisembodiment, because a tapered tip of a lower side of the nozzle body 32is located within the through-hole of the middle body 33, the inflowspace 30 c is formed into an annular shape in cross-section when viewedfrom the center axis direction of the refrigerant inflow passage 31 eand the passage formation member 35.

A suction refrigerant inflow passage connecting the refrigerant suctionport 31 b and the inflow space 30 c extends in a tangential direction ofthe inner peripheral wall surface of the inflow space 30 c when viewedfrom the center axis direction of the inflow space 30 c. With the aboveconfiguration, in this embodiment, the refrigerant flowing into theinflow space 30 c from the refrigerant suction port 31 b through thesuction refrigerant inflow passage is swirled in the same direction asthat of the refrigerant in the swirling space 30 a (upstream swirlingspace 301 and downstream swirling space 302).

The through-hole of the middle body 33 has a part in which a refrigerantpassage area is gradually reduced toward the refrigerant flow directionso as to match an outer peripheral shape of the tapered tip of thenozzle body 32 in an area where the lower side of the nozzle body 32 isinserted, that is, an area in which the middle body 33 and the nozzlebody 32 overlap with each other when viewed in a radial directionperpendicular to the axis line.

Accordingly, a suction passage 30 d is defined between an innerperipheral surface of the through-hole and an outer peripheral surfaceof the lower side of the nozzle body 32, and the inflow space 30 ccommunicates with a downstream side of the depressurizing space 30 b inthe refrigerant flow through the suction passage 30 d. That is, in thisembodiment, a suction passage 13 b that draws the refrigerant from theexternal is defined by the inflow space 30 c, and the suction passage 30d. Further, a cross-section perpendicular to the center axis of thesuction passage 13 b is also formed into an annular shape, and the drawnrefrigerant flows in the suction passage 13 b from the outer peripheralside toward the inner peripheral side of the center axis while swirling.

A pressurizing space 30 e formed into a substantially circular truncatedconical shape that gradually spreads in the refrigerant flow directionis formed in the through-hole of the middle body 33 on the downstreamside of the suction passage 30 d in the refrigerant flow. Thepressurizing space 30 e is a space in which the ejected refrigerantejected from the above-mentioned nozzle passage 13 a is mixed with thesuction refrigerant drawn from the suction passage 30 d.

The lower side of the above-mentioned passage formation member 35 islocated in the interior of the pressurizing space 30 e. Further, aspread angle of the conical-shaped side surface of the passage formationmember 35 in the pressurizing space 30 e is smaller than a spread angleof the circular truncated conical space of the pressurizing space 30 e.Therefore, the refrigerant passage area of the refrigerant passage isgradually enlarged toward the downstream side in the refrigerant flow.

In this embodiment, the refrigerant passage area is enlarged as above.Thus, the refrigerant passage, which is formed between the innerperipheral surface of the middle body 33 and the outer peripheralsurface of the lower side of the passage formation member 35 andconfigures the pressurizing space 30 e, is defined as a diffuser passage13 c which functions as a diffuser. The diffuser passage 13 c convertsvelocity energies of a mixed refrigerant of the ejection refrigerant andthe suction refrigerant into a pressure energy. That is, in the diffuserpassage 13 c, the ejection refrigerant and the suction refrigerant aremixed together, and pressurized. The cross-sectional shape perpendicularto the center axis of the diffuser passage 13 c is also formed into anannular shape.

The refrigerant ejected from the nozzle passage 13 a toward the diffuserpassage 13 c side and the refrigerant drawn from the suction passage 13b have a velocity component in the same swirling direction as that ofthe refrigerant swirling in the swirling space 30 a (upstream swirlingspace 301 and downstream swirling space 302). Therefore, the refrigerantflowing in the diffuser passage 13 c and the refrigerant flowing out ofthe diffuser passage 13 c also have a velocity component in the sameswirling direction as that of the refrigerant swirling in the swirlingspace 30 a (upstream swirling space 301 and downstream swirling space302).

Next, the driving device 37 that is arranged within the middle body 33and displaces the passage formation member 35 will be described. Thedriving device 37 is configured with a circular laminated diaphragm 37 awhich is a pressure responsive member. More specifically, as illustratedin FIG. 2, the diaphragm 37 a is fixed by welding so as to partition acylindrical space defined on the outer peripheral side of the middlebody 33 into two upper and lower spaces.

The upper space (the inflow space 30 c side) of the two spacespartitioned by the diaphragm 37 a configures a sealed space 37 b inwhich a temperature sensitive medium is enclosed. A pressure of thetemperature sensitive medium changes according to a temperature of therefrigerant flowing out of the evaporator 14. A temperature sensitivemedium having the same composition as that of the refrigerantcirculating through the ejector type refrigeration cycle 10 is sealed inthe sealed space 37 b at predetermined density. Accordingly, thetemperature sensitive medium of this embodiment is R134a.

On the other hand, the lower space of the two spaces partitioned by thediaphragm 37 a configures an introduction space 37 c into which therefrigerant flowing out of the evaporator 14 is introduced through anon-shown communication channel. Therefore, the temperature of therefrigerant flowing out of the evaporator 14 is transmitted to thetemperature sensitive medium enclosed in the sealed space 37 b via a capmember 37 d and the diaphragm 37 a that partition the inflow space 30 cand the sealed space 37 b.

In this example, as apparent from FIGS. 2 and 3, the suction passage 13b is arranged on the upper side of the middle body 33 in thisembodiment, and the diffuser passage 13 c is arranged on the lower sideof the middle body 33. Therefore, at least a part of the driving device37 is arranged at a position sandwiched by the suction passage 13 b andthe diffuser passage 13 c from the vertical direction when viewed fromthe radial direction of the axis line.

In more detail, the sealed space 37 b of the driving device 37 isarranged at a position where the suction passage 13 b overlaps with thediffuser passage 13 c and at a position surrounded by the suctionpassage 13 b and the diffuser passage 13 c when viewed from a centeraxis direction of the refrigerant inflow passage 31 e and the passageformation member 35. Accordingly, the temperature of the refrigerantflowing out from the evaporator 14 is transmitted to the sealed space 37b, and an inner pressure in the sealed space 37 b becomes a pressurecorresponding to the temperature of the refrigerant flowing out from theevaporator 14.

Further, the diaphragm 37 a is deformed according to a differentialpressure between the internal pressure of the sealed space 37 b and thepressure of the refrigerant which has flowed into the introduction space37 c from the evaporator 14. For that reason, it is preferable that thediaphragm 37 a is made of a material rich in elasticity, excellent inheat conduction, and tough. For example, it is desirable that thediaphragm 37 a is formed of a metal laminate made of stainless steel(SUS304).

An upper end side of a cylindrical actuating bar 37 e is joined to acenter part of the diaphragm 37 a by welding, and a lower end side ofthe actuating bar 37 e is fixed to an outer peripheral side of thelowermost side (bottom side) of the passage formation member 35. Withthis configuration, the diaphragm 37 a and the passage formation member35 are coupled with each other, and the passage formation member 35 isdisplaced in accordance with a displacement of the diaphragm 37 a toregulate the refrigerant passage area of the nozzle passage 13 a(passage cross-sectional area in the minimum passage area part 30 m).

Specifically, when the temperature (the degree of superheat) of therefrigerant following out of the evaporator 14 rises, a saturatedpressure of the temperature sensitive medium enclosed in the sealedspace 37 b rises to increase a differential pressure obtained bysubtracting the pressure of the introduction space 37 c from theinternal pressure of the sealed space 37 b. Accordingly, the diaphragm37 a displaces the passage formation member 35 in a direction ofenlarging the passage cross-sectional area in the minimum passage areapart 30 m (downward in the vertical direction).

On the other hand, when the temperature (the degree of superheat) of therefrigerant flowing out of the evaporator 14 falls, a saturated pressureof the temperature sensitive medium sealed in the sealed space 37 bfalls to decrease the differential pressure obtained by subtracting thepressure of the introduction space 37 c from the internal pressure ofthe sealed space 37 b. With the above configuration, the diaphragm 37 adisplaces the passage formation member 35 in a direction of reducing thepassage cross-sectional area of the minimum passage area part 30 m(toward the upper side in the vertical direction).

The diaphragm 37 a displaces the passage formation member 35 verticallyaccording to the superheat of the refrigerant flowing out of theevaporator 14 as described above. As a result, the passagecross-sectional area of the minimum passage area part 30 m is adjustedso that the degree of superheat of the refrigerant flowing out of theevaporator 14 comes closer to a predetermined value. A gap between theactuating bar 37 e and the middle body 33 is sealed by a seal membersuch as an O-ring not shown, and the refrigerant is not leaked throughthe gap even if the actuating bar 37 e is displaced.

The bottom of the passage formation member 35 is subjected to a load ofa coil spring 40 fixed to the lower body 34. The coil spring 40 exertsthe load urging the passage formation member 35 so as to reduce thepassage cross-sectional area in the minimum passage area part 30 m(upper side in FIG. 2). With the regulation of this load, a valveopening pressure of the passage formation member 35 can be changed tochange a target degree of superheat.

Incidentally, in this embodiment, the multiple (specifically, two asillustrated in FIGS. 2 and 3) cylindrical spaces are provided in thepart of the middle body 33 on the radially outer side, and therespective circular laminated diaphragms 37 a are fixed in those spacesto configure two driving devices 37. However, the number of drivingdevices 37 is not limited to this number. When the driving devices 37are provided at plural locations, it is desirable that the drivingdevices 37 are arranged at regular angular intervals with respect to therespective center axes.

Alternatively, a diaphragm formed of the annular thin plate may be fixedin a space having an annular shape when viewed from the center axisdirection, and the diaphragm and the passage formation member 35 may becoupled with each other by multiple actuating bars.

Next, the lower body 34 is formed of a circular-cylindrical metalmember, and fixed in the housing body 31 by screwing so as to close abottom of the housing body 31. As illustrated in FIGS. 2 and 3, thegas-liquid separation space 30 f that separates gas and liquid of therefrigerant that has flowed out of the above-mentioned diffuser passage13 c from each other is defined between the upper side of the lower body34 and the middle body 33.

The gas-liquid separation space 30 f is defined as a space of asubstantially cylindrical rotating body shape, and the center axis ofthe gas-liquid separation space 30 f is also arranged coaxially with thecenter axes of the refrigerant inflow passage 31 e and the passageformation member 35.

As described above, the refrigerant, which flows out from the diffuserpassage 13 c and flows into the gas-liquid separation space 30 f, hasthe velocity component of the refrigerant swirling in the same directionas the swirl direction of the refrigerant swirling in the swirling space30 a (upstream swirling space 301 and downstream swirling space 302).Accordingly, gas and liquid of the refrigerant in the gas-liquidseparation space 30 f are separated by action of a centrifugal force.

A hollow cylindrical pipe 34 a that is arranged coaxially with thegas-liquid separation space 30 f and extends upward is disposed in thecenter part of the lower body 34. The liquid-phase refrigerant separatedin the gas-liquid separation space 30 f is accumulated on a radiallyouter side of the pipe 34 a. Also, a gas-phase refrigerant outflowpassage 34 b is formed inside the pipe 34 a and guides the gas-phaserefrigerant separated in the gas-liquid separation space 30 f to thegas-phase refrigerant outlet port 31 d of the housing body 31.

Further, the above-mentioned coil spring 40 is fixed to an upper end ofthe pipe 34 a. The coil spring 40 also functions as a vibrationabsorbing member that attenuates the vibration of the passage formationmember 35, which is caused by a pressure pulsation generated when therefrigerant is depressurized. An oil return hole 34 c that returns arefrigerator oil in the liquid-phase refrigerant into the compressor 11through the gas-phase refrigerant outflow passage 34 b is formed on abase part (lowermost part) of the pipe 34 a.

The liquid-phase refrigerant outlet port 31 c of the ejector 13 isconnected with an inlet side of the evaporator 14 as illustrated inFIG. 1. The evaporator 14 is a heat-absorbing heat exchanger thatevaporates a low-pressure refrigerant depressurized by the ejector 13and performs a heat absorbing effect by exchanging heat between thelow-pressure refrigerant and blast air that is blown into the vehicleinterior from a blower fan 14 a.

The blower fan 14 a is an electric blower of which the rotation speed(the amount of blast air) is controlled by a control voltage output fromthe control device. The refrigerant suction port 31 b of the ejector 13is connected to an outlet side of the evaporator 14. Further, thegas-phase refrigerant outlet port 31 d of the ejector 13 is connectedwith the intake side of the compressor 11.

Next, the control device (not shown) includes a well-known microcomputerincluding a CPU, a ROM and a RAM, and peripheral circuits of themicrocomputer. The control device controls the operations of theabove-mentioned various electric actuators 11 b, 12 d, and 14 a and thelike by performing various calculations and processing on the basis of acontrol program stored in the ROM.

Further, an air conditioning control sensor group such as an inside airtemperature sensor for detecting a vehicle interior temperature, anoutside air temperature sensor for detecting the temperature of outsideair, an insolation sensor for detecting the amount of insolation in thevehicle interior, an evaporator-temperature sensor for detecting theblow-out air temperature from the evaporator 14 (the temperature of theevaporator), an outlet-side temperature sensor for detecting thetemperature of a refrigerant on the outlet side of the heat radiator 12,and an outlet-side pressure sensor for detecting the pressure of arefrigerant on the outlet side of the heat radiator 12, is connected tothe control device. Accordingly, detection values of the sensor groupare input to the control device.

Furthermore, an operation panel (not shown), which is disposed near adashboard panel positioned at the front part in the vehicle interior, isconnected to the input side of the control device, and operation signalsoutput from various operation switches mounted on the operation panelare input to the control device. An air conditioning operation switchthat is used to perform air conditioning in the vehicle interior, avehicle interior temperature setting switch that is used to set thetemperature of the vehicle interior, and the like are provided as thevarious operation switches that are mounted on the operation panel.

Meanwhile, the control device of this embodiment is integrated with acontrol unit for controlling the operations of various control targetdevices connected to the output side of the control device, but astructure (hardware and software), which controls the operations of therespective control target devices, of the control device forms thecontrol unit of the respective control target devices. For example, astructure (hardware and software), which controls the operation of theelectric motor 11 b of the compressor 11, forms a discharge capabilitycontrol unit in this embodiment.

Next, the operation of this embodiment having the above-mentionedconfiguration will be described with reference to a Mollier diagram ofFIG. 5. A vertical axis of the Mollier diagram indicates pressurescorresponding to P0, P1, and P2 of FIG. 3. First, when an operationswitch of an operation panel is turned on, the control device operatesthe electric motor 11 b of the compressor 11, the cooling fan 12 d, theblower fan 14 a, or the like. Accordingly, the compressor 11 draws andcompresses a refrigerant and discharges the refrigerant.

The gas-phase refrigerant (point a5 in FIG. 5), which is discharged fromthe compressor 11 and has a high temperature and a high pressure, flowsinto the condenser 12 a of the heat radiator 12 and is condensed byexchanging heat between the blast air (outside air), which is blown fromthe cooling fan 12 d, and itself and by radiating heat. Gas and liquidof the refrigerant radiated by the condenser 12 a are separated by thereceiver part 12 b. A liquid-phase refrigerant, which has been subjectedto gas-liquid separation in the receiver part 12 b, is changed into asubcooled liquid-phase refrigerant by exchanging heat between the blastair, which is blown from the cooling fan 12 d, and itself in thesubcooling portion 12 c and further radiating heat (from point a5 topoint b5 in FIG. 5).

The subcooled liquid-phase refrigerant that has flowed out of thesubcooling portion 12 c of the heat radiator 12 is isentropicallydepressurized by the nozzle passage 13 a, and ejected (from point b5 topoint c5 in FIG. 5). The nozzle passage 13 a is formed between the innerperipheral surface of the depressurizing space 30 b of the ejector 13and the outer peripheral surface of the passage formation member 35. Inthis situation, the refrigerant passage area in the minimum passage areapart 30 m of the depressurizing space 30 b is regulated so that thedegree of superheat of the refrigerant on the outlet side of theevaporator 14 comes close to a predetermined given value.

The refrigerant that has flowed out of the evaporator 14 is drawnthrough the refrigerant suction port 31 b and the suction passage 13 b(in more detail, the inflow space 30 c and the suction passage 30 d) dueto the suction action of the ejection refrigerant which has been ejectedfrom the nozzle passage 13 a. In addition, the ejection refrigerantejected from the nozzle passage 13 a and the suction refrigerant drawnthrough the suction passage 13 b and the like flow into the diffuserpassage 13 c (from point c5 to point d5, and from point h5 to point d5in FIG. 5).

In the diffuser passage 13 c, the velocity energy of the refrigerant isconverted into the pressure energy due to the enlarged refrigerantpassage area. As a result, the mixed refrigerant is pressurized whilethe ejection refrigerant and the suction refrigerant are mixed together(from point d5 to point e5 in FIG. 5). The refrigerant that has flowedout of the diffuser passage 13 c is separated into gas and liquid in thegas-liquid separation space 30 f (from point e5 to point f5, and frompoint e5 to point g5 in FIG. 5).

The liquid-phase refrigerant that has been separated in the gas-liquidseparation space 30 f flows out of the liquid-phase refrigerant outletport 31 c, and flows into the evaporator 14. The refrigerant which hasflowed into the evaporator 14 absorbs heat from blown air blown by theblower fan 14 a, is evaporated, and cools the blast air (point g5 topoint h5 in FIG. 5). On the other hand, the gas-phase refrigerant thathas been separated in the gas-liquid separation space 30 f flows out ofthe gas-phase refrigerant outlet port 31 d, and is drawn into thecompressor 11 and compressed again (point f5 to point a5 in FIG. 5).

The ejector refrigeration cycle 10 according to this embodiment operatesas described above, and can cool the blast air to be blown into thevehicle interior. Further, in the ejector refrigeration cycle 10, sincethe refrigerant pressurized by the diffuser passage 13 c is drawn intothe compressor 11, the drive power of the compressor 11 can be reducedto improve the cycle of performance (COP).

According to the ejector 13 of this embodiment, the fluid swirls in theupstream swirling space 301 and the downstream swirling space 302 withthe result that a fluid pressure in the downstream swirling space 302 onthe swirling center side can be reduced to a pressure at which therefrigerant is depressurized and boiled (cavitation is generated).Further, the refrigerant in the gas-liquid mixing state where thegas-phase refrigerant and the liquid-phase refrigerant in the downstreamswirling space 302 on the swirling center side are mixed together isallowed to flow into the nozzle passage 13 a, and can be depressurized.

Therefore, even a state of the refrigerant flowing into the swirlingspace 30 a (specifically, the upstream swirling space 301) changes dueto a change in the outside temperature, the density of the refrigerantflowing into the nozzle passage 13 a is restrained from largelychanging, and a variation in the flow rate of the ejected refrigerantejected from the nozzle passage 13 a can be suppressed.

According to the configuration of the nozzle passage 13 a of the ejector13 of this embodiment, a state of the refrigerant in the vicinity of theminimum passage area part 30 m approaches the gas-liquid mixing state inwhich the gas-phase refrigerant and the liquid-phase refrigerant arehomogeneously mixed together, and blocking (choking) is generated in aflow of the refrigerant of the gas-liquid mixing state. As a result, theflow rate of the refrigerant can be accelerated to the sound velocity orhigher.

Further, the refrigerant in the gas-liquid mixing state which is asupersonic state flows into the divergent portion 132 so as to befurther accelerated and ejected. Therefore, the effective improvement inthe energy conversion efficiency in converting the pressure energy ofthe refrigerant into the velocity energy in the nozzle passage 13 a canbe expected.

However, when a boiling delay is generated in the liquid-phaserefrigerant flowing into the nozzle passage 13 a, a flow of therefrigerant cannot be choked in the vicinity of the minimum passage areapart 30 m of the nozzle passage 13 a, the energy conversion efficiencyin the nozzle passage 13 a may be lowered.

On the contrary, in the ejector 13 of this embodiment, since thesectional shape of the outlet part 38 e for allowing the refrigerant toflow out of the upstream swirling space 301 is formed into an annularshape along the outer peripheral shape of the upstream swirling space301, the refrigerant flowing out of the upstream swirling space 301 canflow in the axial direction from the outer peripheral side of thedownstream swirling space 302 as indicated by solid arrows in FIG. 3.

With the above configuration, the refrigerant flowing out of theupstream swirling space 301 can be restrained from flowing toward theswirling center side of the downstream swirling space 302. Further, therefrigerant flowing out of the upstream swirling space 301 can mergeinto the flow from the outer peripheral side of the downstream swirlingspace 302 toward the nozzle passage 13 a side, of the flow (flowindicated by dashed arrows in FIG. 3) of the liquid-phase refrigerantstaying while circulating in the downstream swirling space 302.

Therefore, the flow of refrigerant staying while circulating in thedownstream swirling space 302 is not blocked by the refrigerant flowingfrom the upstream swirling space 301 into the downstream swirling space302, and the ratio of the gas-phase refrigerant to the refrigerant inthe gas-liquid mixing state flowing into the nozzle passage 13 a can berestrained from being lowered. As a result, the boiling of theliquid-phase refrigerant in the nozzle passage 13 a is promoted, and theenergy conversion efficiency in the nozzle passage 13 a can berestrained from being lowered.

In the ejector 13 according to this embodiment, the upstream swirlingspace 301 is defined in a space between the upper plate 38 a and thelower plate 38 b, and the swirling promotion member 38 that swirls therefrigerant within the upstream swirling space 301 around the centeraxis by allowing the refrigerant on the center side of the upstreamswirling space 301 to flow toward the outer peripheral side along theplate surface of the flow regulating plates 38 c is provided.

Therefore, the shape of the outlet part 38 e for allowing therefrigerant to flow out of the upstream swirling space 301 can be easilyformed into an annular shape along the outer peripheral shape of theupstream swirling space 301. Further, since there is no need to providethe space for generating the swirling flow of the refrigerant outsidethe upstream swirling space 301, the body size can be restrained frombeing upsized as the overall ejector 13.

In addition, the ejector 13 of this embodiment employs the passageformation member 35 having a conical shape of which a cross-sectionalarea increases with distance from the depressurizing space 30 b. Thecross-sectional shape of the diffuser passage 13 c is formed in anannular shape. Therefore, the diffuser passage 13 c can have a shape tospread along the outer periphery of the passage formation member 35 in adirection away from the depressurizing space 30 b.

Therefore, the dimension of the diffuser passage 13 c in an axialdirection (axial direction of the passage formation member 35) can berestrained from increasing. As a result, the upsizing of the body of theoverall ejector 13 can be limited.

The gas-liquid separation space 30 f that separates gas and liquid ofthe refrigerant that has flowed out of the diffuser passage 13 c isformed in the body 30 of the ejector 13 according to this embodiment.Hence, the capacity of the gas-liquid separation space 30 f can beeffectively reduced as compared with a case in which a gas-liquidseparation device is provided in addition to the ejector 13.

That is, in the gas-liquid separation space 30 f according to thisembodiment, since the refrigerant that flows out of the diffuser passage13 c annular in cross-section already has the velocity component in aswirling direction, there is no need to provide a space for generatingthe swirling flow of the refrigerant in the gas-liquid separation space30 f. Therefore, the capacity of the gas-liquid separation space 30 fcan be effectively reduced as compared with the case in which thegas-liquid separation device is provided apart from the ejector 13.

Second Embodiment

In the first embodiment, the example in which the swirling flow of therefrigerant is generated in the interior of the upstream swirling space301 is described. In this embodiment, a description will be given of anexample in which, as illustrated in FIGS. 6 to 8, with the applicationof a swirling promotion member 39, a swirling flow of the refrigerant isgenerated in the outer peripheral side of the upstream swirling space301, and the refrigerant having a velocity component in the swirlingdirection flows into the upstream swirling space 301. FIGS. 6 to 8correspond to FIGS. 2 to 4 in the first embodiment, respectively, andthe same or equivalent parts to those in the first embodiment aredenoted by identical symbols.

Specifically, a swirling promotion member 39 according to thisembodiment includes a plate 39 a formed into a disc shape, multiple flowregulating plates 39 b projected downward from an outer peripheral partof the plate 39 a, and a cylindrical protruding portion 39 c projectedfrom a center part of the plate 39 a toward the same direction(downward) as that of the flow regulating plates 39 b. The amount ofprojection from the plate 39 a of the protruding portion 39 c is equalto or larger than the amount of projection of the flow regulating plates39 b.

An outer diameter of the refrigerant inflow passage 31 e according tothis embodiment is formed to be larger than an outer diameter of a spacedefined in the interior of the nozzle body 32, and an outer diameter ofthe plate 39 a is formed to be smaller than an outer diameter of therefrigerant inflow passage 31 e. Therefore, a gap formed into an annularshape when viewed from the axial direction of the refrigerant inflowpassage 31 e is defined between an outer peripheral side of the plate 39a and an inner peripheral wall surface of the refrigerant inflow passage31 e. The annular gap configures an inlet part 39 d for allowing therefrigerant flowing from the refrigerant inlet port 31 a toward thenozzle body 32 side.

As illustrated in FIG. 8, the multiple flow regulating plates 39 b arearranged in an annular shape around the center axis of the refrigerantinflow passage 31 e. Further, the plate surfaces of the respective flowregulating plates 39 b are so tilted or curved as to swirl a flow of therefrigerant around the center axis when viewed from the center axisdirection. Those flow regulating plates 39 b are disposed in an areaextending from an outer periphery of the plate 39 a to an outerperiphery of a space defined in the interior of the nozzle body 32 whenviewed from the center axis direction.

The center axis of the protruding portion 39 c is disposed coaxiallywith the center axis of the refrigerant inflow passage 31 e, and anouter diameter of the protruding portion 39 c is formed to be smallerthan an outer diameter of the space defined in the interior of thenozzle body 32. Therefore, a hollow cylindrical gap space formed in anannular shape in a cross-section perpendicular to the center axisdirection is defined between the inner peripheral side of the multipleflow regulating plates 39 b disposed annularly and the outer peripheralside of the protruding portion 39 c.

Therefore, the refrigerant flowing into the refrigerant inflow passage31 e from the refrigerant inlet port 31 a flows into the outerperipheral side of the multiple flow regulating plates 39 b disposedannularly through the inlet part 39 d on the outer peripheral side ofthe plate 39 a. Further, the refrigerant flowing into the outerperipheral side of the multiple flow regulating plates 39 b flows towardthe inner peripheral side of the multiple flow regulating plates 39 b.In this situation, the refrigerant flows along the plate surfaces of themultiple flow regulating plates 39 b whereby the refrigerant swirlsaround the center axis.

The refrigerant flowing into the inner peripheral side of the multipleflow regulating plates 39 b flows into the hollow cylindrical gap spacedefined between the inner peripheral side of the multiple flowregulating plates 39 b and the outer peripheral side of the protrudingportion 39 c. The refrigerant flowing into the hollow cylindrical gapspace flows into the space below (downstream side) of the swirlingpromotion member 39 from a lowermost side of the hollow cylindrical gapspace while swirling around the center axis. Further, the refrigerantflowing into the space below the swirling promotion member 39 isintroduced into the nozzle passage 13 a side to be described later whileswirling around the center axis.

As is apparent from the above description, in this embodiment, asillustrated in FIG. 7, the hollow cylindrical gap space defined betweenthe inner peripheral side of the flow regulating plates 39 b and theouter peripheral side of the protruding portion 39 c is an example ofthe upstream swirling space 301 in which the refrigerant flowing fromthe external is swirled.

As illustrated in FIG. 8, the outlet part 39 e disposed on a lowermostpart (downstream side) of the hollow cylindrical gap space (upstreamswirling space 301) for allowing the refrigerant to flow out of theupstream swirling space 301 is formed into an annular shape similar tothe cross-sectional shape of the upstream swirling space 301 in a crosssectional surface perpendicular to the axial direction, that is, anannular shape along the outer peripheral shape of the upstream swirlingspace 301.

Further, the space below (downstream of) the swirling promotion member39 is an example of a downstream swirling space 302 for introducing therefrigerant flowing out of the upstream swirling space 301 toward thedepressurizing space 30 b side while swirling. The other configurationand operation of the ejector 13 and the ejector refrigeration cycle 10are similar to those of the first embodiment.

Therefore, even in the ejector 13 according to this embodiment, as inthe first embodiment, the refrigerant (flow indicated by thick solidarrows in FIG. 7) flowing out of the upstream swirling space 301 canmerge into the flow from the outer peripheral side of the downstreamswirling space 302 toward the nozzle passage 13 a side, of the flow(flow indicated by dashed arrows in FIG. 7) of the liquid-phaserefrigerant staying and circulating in the downstream swirling space302. As a result, as in the first embodiment, a reduction in the energyconversion efficiency in the nozzle passage 13 a can be limited.

In the ejector 13 according to this embodiment, since the upstreamswirling space 301 is formed into the rotating body shape that isannular in the cross-sectional surface perpendicular to the center axisdirection, the shape of the outlet part 38 e for allowing therefrigerant to flow out of the upstream swirling space 301 can be easilyformed into an annular shape along the outer peripheral shape of theupstream swirling space 301.

Further, the swirling flow of the refrigerant is generated on the outerperipheral side of the upstream swirling space 301, and the refrigeranthaving the velocity component in a direction of swirling around thecenter axis flows into the upstream swirling space 301. Therefore, whena configuration in which the swirling flow of the refrigerant isgenerated in the interior of the upstream swirling space 301 isdisposed, the degree of freedom of design of the configuration in whichthe swirling flow of the refrigerant is generated can be improved.

Third Embodiment

In the ejector refrigeration cycle 10 a of this embodiment, asillustrated in an overall configuration diagram of FIG. 9, the ejector13 according to the first embodiment is replaced with an ejector 53 anda gas-liquid separator 60.

The ejector 53 according to this embodiment does not have a function ofthe gas-liquid separator, but as in the ejector 13 of the firstembodiment, performs a function of a refrigerant depressurizing deviceand also performs a function of a refrigerant circulation device(refrigerant transport device). A specific configuration of the ejector53 will be described with reference to FIG. 10.

The ejector 53 has a nozzle 531 and a body 532 as illustrated in FIG.10. First, the nozzle 531 is made of metal (for example, stainlessalloy) shaped into substantially a hollow cylinder gradually taperedtoward a flowing direction of the refrigerant, and the refrigerantflowing into the nozzle 531 is isentropically depressurized, and ejectedfrom a refrigerant ejection port 531 a defined on the most downstreamside in the refrigerant flow.

The interior of the nozzle 531 is formed with a swirling space 531 c inwhich the refrigerant flowing from a refrigerant inlet port 531 bswirls, and a refrigerant passage in which the refrigerant flowing outof the swirling space 531 c is depressurized.

In detail, the swirling space 531 c is formed in the interior of acylindrical part 531 g disposed on the upstream side of the nozzle 531in the refrigerant flow. Therefore, the cylindrical part 531 g may beused as an example of a swirling space formation member having theswirling space 531 c, and in this embodiment, the swirling spaceformation member and the nozzle are integrated with each other.

Further, a cylindrical member 531 h formed into a cylindrical shapesmaller than an inner diameter of the cylindrical part 531 g is disposedon the upstream side in the refrigerant flow in the interior of thecylindrical part 531 g. The axial length of the cylindrical member 531 his formed to be shorter than an axial length of the cylindrical part 531g, and disposed coaxially with a center axis of the cylindrical part 531g.

Therefore, in an area where the cylindrical part 531 g overlaps with thecylindrical member 531 h when viewed from the radial direction, a hollowcylindrical space formed into an annular shape in a cross-sectionperpendicular to the center axis direction is defined between the innerperipheral side of the cylindrical part 531 g and the outer peripheralside of the cylindrical member 531 h. In an area where the cylindricalpart 531 g does not overlap with the cylindrical member 531 h, acylindrical space formed into a circular shape in a cross-sectionperpendicular to the center axis direction is defined on the innerperipheral side of the cylindrical part 531 g.

Further, a refrigerant inflow passage that connects the refrigerantinlet port 531 b and the swirling space 531 c is opened in the hollowcylindrical space, and extends in a tangential direction of an innerwall surface of the swirling space 531 c when viewed from a center axisdirection of the swirling space 531 c.

With the above configuration, the refrigerant flowing into the hollowcylindrical space from the refrigerant inlet port 531 b flows along aninner peripheral wall surface of the cylindrical part 531 g, and swirlsabout a center axis of the cylindrical part 531 g. Further, therefrigerant flowing out of the hollow cylindrical space flows into thecylindrical space while swirling around the center axis.

As is apparent from the above description, in this embodiment, thehollow cylindrical space within the cylindrical part 531 g is an exampleof an upstream swirling space 311 in which the refrigerant flowing outof the external is swirled, and the cylindrical space within thecylindrical part 531 g is an example of a downstream swirling space 312that introduces the refrigerant flowing out of the upstream swirlingspace 311 into a minimum passage area part 531 d of the nozzle 531 whileswirling.

An outlet part 311 a disposed on the most downstream side of the hollowcylindrical space (upstream swirling space 311) for allowing therefrigerant to flow out of the upstream swirling space 311 is formedinto an annular shape similar to the cross-sectional shape of theupstream swirling space 311 in a cross sectional surface perpendicularto the axial direction, that is, an annular shape along the outerperipheral shape of the upstream swirling space 311.

In this example, since the downstream swirling space 312 is formed intothe hollow rotating body shape, a refrigerant pressure on the centeraxis side is reduced more than the refrigerant pressure on the outerperipheral side due to the action of a centrifugal force generated byswirling the refrigerant in the downstream swirling space 312.Accordingly, in this embodiment, in a normal operation of the ejectorrefrigeration cycle 10, the refrigerant pressure on the center axis sidein the downstream swirling space 312 is reduced to a pressure at whichthe refrigerant is depressurized and boiled (cavitation is generated).

The adjustment of the refrigerant pressure on the center axis side inthe downstream swirling space 312 can be realized by adjusting theswirling flow rate of the refrigerant swirling in the downstreamswirling space 312. Further, the swirling flow rate can be adjusted by,for example, adjusting an area ratio of the passage sectional area ofthe refrigerant inflow passage to the sectional area of the downstreamswirling space 312 perpendicular to the axial direction. Meanwhile, theswirling flow rate in this embodiment means the flow rate of therefrigerant in the swirling direction in the vicinity of the outermostperipheral part of the swirling space 531 c.

Further, the refrigerant passage defined in the interior of the nozzle531 is formed with the minimum passage area part 531 d having arefrigerant passage area most reduced, a tapered part 531 e having arefrigerant passage area gradually reduced toward the minimum passagearea part 531 d from the swirling space 531 c, and a divergent part 531f having a refrigerant passage area gradually enlarged from the minimumpassage area part 531 d toward the refrigerant ejection port 531 a.

The body 532 is made of metal (for example, aluminum) or resin formedinto substantially a hollow cylindrical shape, functions as a fixingmember for internally supporting and fixing the nozzle 531, and forms anouter shell of the ejector 53. More specifically, the nozzle 531 isfixed by press fitting so as to be housed in the interior of the body532 on one end side in the longitudinal direction of the body 532.

A refrigerant suction port 532 a is defined in a portion correspondingto an outer peripheral side of the nozzle 531 on an outer peripheralside surface of the body 532. The refrigerant suction port 532 a is athrough-hole that penetrates through a portion corresponding to an outerperipheral side of the nozzle 531 on the outer peripheral side surfaceof the body 532, and disposed to communicate with the refrigerantejection port 531 a of the nozzle 531. The refrigerant suction port 532a draws the refrigerant flowing out of an evaporator 14 into theinterior of the ejector 53 due to the suction action of the ejectionrefrigerant ejected from the refrigerant ejection port 531 a of thenozzle 531. The refrigerant suction port 532 a may be used as an exampleof the fluid suction port for drawing the fluid due to the suctionaction of the ejected fluid at a high speed which is ejected from thenozzle 531.

Further, the body 532 internally includes a diffuser portion 532 b thatmixes the ejection refrigerant ejected from the refrigerant ejectionport 531 a with the suction refrigerant drawn from the refrigerantsuction port 532 a to increase the pressure, and a suction passage 532 cthat introduces the suction refrigerant drawn from the refrigerantsuction port 532 a into the diffuser portion 532 b. The diffuser portion532 b may be used as an example of a pressure increase part for mixingand pressurizing the ejection fluid ejected from the nozzle 531 with thesuction fluid drawn from the fluid suction port.

The suction passage 532 c is formed by a space between an outerperipheral side around a tip of a tapered shape of the nozzle 531 and aninner peripheral side of the body 532. A refrigerant passage area of thesuction passage 532 c is gradually reduced toward the refrigerant flowdirection. With the above configuration, a flow rate of the suctionrefrigerant flowing in the suction passage 532 c is graduallyaccelerated, and an energy loss (mixing loss) in mixing the suctionrefrigerant with the ejection refrigerant is reduced by the diffuserportion 532 b.

The diffuser portion 532 b is disposed to be continuous to an outletside of the suction passage 532 c, and formed so that a refrigerantpassage area gradually increases. This configuration performs a functionof converting a velocity energy of a mixed refrigerant of the ejectionrefrigerant and the suction refrigerant into a pressure energy, that is,functions as a pressure increase part that decelerates a flow rate ofthe mixed refrigerant, and pressurizes the mixed refrigerant.

More specifically, a wall surface shape of the inner peripheral wallsurface of the body 532 forming the diffuser portion 532 b according tothis embodiment is defined by the combination of multiple curves asillustrated in a cross-section along the axial direction in FIG. 2. Aspread degree of the refrigerant passage cross-sectional area of thediffuser portion 532 b gradually increases toward the refrigerant flowdirection, and thereafter again decreases, as a result of which therefrigerant can be isentropically pressurized.

As illustrated in FIG. 9, a refrigerant outlet side of the diffuserportion 532 b of the ejector 53 is connected with a refrigerant inletport of the gas-liquid separator 60. The gas-liquid separator 60 is agas-liquid separation device that separates gas and liquid of therefrigerant flowing into the interior of the gas-liquid separator 60from each other.

A liquid-phase refrigerant outlet port of the gas-liquid separator 60 isconnected with the refrigerant inlet side of the evaporator 14. Thegas-phase refrigerant outlet port of the gas-liquid separator 60 isconnected with an inlet side of the compressor 11. Other structures andoperations are the same as those of the first embodiment.

Therefore, in the ejector 53 according to this embodiment, as in thefirst embodiment, the refrigerant flowing out of the upstream swirlingspace 311 (a flow indicated by dashed arrows in FIG. 10) can merge intothe flow from the outer peripheral side of the downstream swirling space312 toward the minimum passage area part 531 d side of the nozzle 531,of the flow (flow indicated by dashed arrows in FIG. 10) of theliquid-phase refrigerant staying and circulating in the downstreamswirling space 312. As a result, as in the first embodiment, a reductionin the nozzle efficiency of the nozzle 531 can be limited.

The present disclosure is not limited to the above-describedembodiments, but various modifications can be made thereto as followswithout departing from the spirit of the present disclosure.

(1) In the first and second embodiments, the examples in which theupstream swirling space 301 and the downstream swirling space 302 aredefined by the swirling promotion members 38 and 39, respectively, aredescribed. However, the upstream swirling space 301 and the downstreamswirling space 302 are not limited to the above configurations.

For example, in the ejector 13 according to the first and secondembodiments, the refrigerant inflow passage 31 e is defined to extend inthe tangential direction of the inner wall surface of the swirling space30 a, and the same cylindrical member as that in the third embodiment isdisposed in the interior of the swirling space 30 a. The hollowcylindrical space defined in the area where the swirling space 30 aoverlaps with the cylindrical member may be defined as the upstreamswirling space 301, and the cylindrical space defined in the area wherethe swirling space 30 a does not overlap with the cylindrical member maybe defined as the downstream swirling space 302.

In the ejector 53 according to the third embodiment, the swirlingpromotion members 38 and 39 according to the first and secondembodiments are disposed in the interior of the cylindrical part 531 g.As a result, as in the first and second embodiments, the upstreamswirling space 311 and the downstream swirling space 312 may be defined.

(2) In the above first and second embodiments, the description has beengiven of the example in which the driving device 37 that displaces thepassage formation member 35 includes the sealed space 37 b in which thetemperature sensitive medium having the pressure changed according to achange in the temperature is sealed, and the diaphragm 37 a that isdisplaced according to the pressure of the temperature sensitive mediumwithin the sealed space 37 b. However, the driving device is not limitedto this configuration.

For example, a thermo wax that changes a volume with temperature as atemperature sensitive medium may be applied, or the driving deviceformed of a shape memory alloy elastic member as a driving device may beapplied. Furthermore, the driving device in which the passage formationmember 35 is displaced by an electric motor may be applied as thedriving device as in the second embodiment.

(3) In the above-mentioned third embodiment, a detail of the arrangementof the ejector 53 is not described. In the arrangement of the ejector53, the axial direction of the nozzle 531 may be disposed in parallel toa vertical direction as in the first and second embodiments, or may bedisposed in parallel to another direction (for example, a horizontaldirection). This is because the refrigerant swirling within the swirlingspace 531 c is unlikely to be affected by a gravity force because theswirling speed is relatively high.

(4) In the above embodiments, the details of the liquid-phaserefrigerant outlet port 31 c of the ejector 13 and the gas-phaserefrigerant outlet port of the gas-liquid separator 60 are notdescribed. A depressurizing device (for example, side fixed apertureformed of an orifice or a capillary tube) for depressurizing therefrigerant may be arranged on those refrigerant outlet ports.

(5) In the above embodiments, the example in which the ejectorrefrigeration cycle 10 including the ejector 13 of the presentdisclosure is applied to a vehicle air conditioning apparatus has beendescribed, but the application of the ejector refrigeration cycle 10having the ejector 13 of the present disclosure is not limited to thisconfiguration. For example, the ejector refrigeration cycle 10 may beapplied to, for example, a stationary air conditioning apparatus, coldstorage warehouse, a cooling heating device for a vending machine, etc.

(6) Examples in which a subcooling heat exchanger is employed as theheat radiator 12 have been described in the above-mentioned embodiments,but, needless to say, a normal heat radiator formed of only thecondenser 12 a may be employed as the heat radiator 12. In theabove-described embodiments, the example in which components such as thebody 30 of the ejector 13, and components such as the nozzle 531 of theejector 53 and the body 532 are formed of metal is described. However,as long as functions of the components can be exerted, the materials arenot limited. Accordingly, those components may be made of a resin.

The present disclosure has been made based on the following analyticalfindings. First, the present inventors have confirmed a flow of therefrigerant within the swirling space when the refrigerant pressure onthe swirling center side is reduced down to a pressure at which therefrigerant is depressurized and boiled by swirling the refrigerant forrefrigeration cycle in the swirling space of the depressurizing deviceby simulation analysis.

FIG. 11 is a cross-sectional view along an axial direction of a swirlingspace 70 d showing a result of the simulation analysis, in which an areain which the liquid-phase refrigerant is present is indicated by dothatching, and flow lines of the refrigerant in that area is indicated byrespective arrows.

The flow lines indicated by the respective arrows are flow linesillustratable in a cross-section in the axial direction in FIG. 11, thatis, flow lines that can be drawn by velocity components from which avelocity component in the swirling direction is removed. The swirlingspace 70 d is defined within a main body 70 a of a depressurizing device70, and formed into a hollow rotating body shape (in more detail, ashape in which a cylindrical space is coupled coaxially with a conicalspace).

It is confirmed from FIG. 11 that a gas-phase refrigerant is unevenlydistributed in a columnar shape on a swirling center side of theswirling space 70 d. A liquid-phase refrigerant around the gas-phaserefrigerant (hereinafter referred to as “gas column”) unevenlydistributed in the columnar shape flows from a minimum passage area part70 b side that is one end side along the gas column in the axialdirection (lower side in FIG. 11) toward the other end side in the axialdirection (upper side in FIG. 11) as indicated by the flow lines ofdashed arrows.

Further, the refrigerant that flows along the gas column and reaches theother end side in the axial direction flows on an outer peripheral sideof the swirling space 70 d, and flows toward the minimum passage areapart 70 b side from the outer peripheral side. The refrigerant thatreaches the minimum passage area part 70 b side again flows from theminimum passage area part 70 b side toward the other end side in theaxial direction along the gas column. In other words, it can beconfirmed that the liquid-phase refrigerant around the gas column stayswhile circulating around the gas column as indicated by dashed arrows inFIG. 11.

As described above, the liquid-phase refrigerant around the gas columnstays while circulating, and the liquid-phase refrigerant flows alongthe gas column from the minimum passage area part 70 b side toward theother end side in the axial direction. Therefore, it is understood thatan angular momentum of the swirling flow of the refrigerant in thevicinity of the minimum passage area part 70 b is transmitted to therefrigerant in an overall area on the swirling center side in the axialdirection. Further, it is understood that the depressurization andboiling of the refrigerant in the overall area on the swirling centerside in the axial direction are promoted by the transmission of theangular momentum, and the gas column is formed over the overall areawithin the swirling space 70 d in the axial direction.

On the other hand, the refrigerant flowing from a refrigerant inlet port70 c connected to a side surface of the main body 70 a into the swirlingspace 70 d flows toward the minimum passage area part 70 b side alongthe outer peripheral side of the refrigerant staying while circulatingaround the gas column as shown by flow lines indicated by thick solidarrows in FIG. 11.

In this situation, since the refrigerant flowing into the swirling space70 d is a high pressure refrigerant flowing out of the radiator, even ifthe refrigerant flows in the tangential direction of the swirling space70 d circular in the cross-section, the refrigerant flowing into theswirling space 70 d is liable to flow toward the low pressure side (thatis, swirling center side) under an operation condition where a pressureof the high pressure refrigerant is relatively high as in a high loadoperation of the refrigeration cycle device.

When the refrigerant flowing into the swirling space 70 d flows towardthe swirling center side, a flow of the liquid-phase refrigerantcirculating around the gas column is blocked as indicated by a thicksolid arrow on a right side in FIG. 11. For that reason, the angularmomentum of the swirling flow of the refrigerant in the vicinity of theminimum passage area part 70 b described above is unlikely to betransmitted to the refrigerant in the overall area on the swirlingcenter side in the axial direction, and the depressurization and boilingof the refrigerant on the swirling center side may be limited.

As a result, a ratio of the gas-phase refrigerant to the refrigerant inthe gas-liquid mixing state which flows in the minimum passage area partis lowered, and the nozzle efficiency may be lowered. The refrigerant inthe gas-liquid mixing state does not mean only the refrigerant in agas-liquid two-phase state, but includes the refrigerant in a statewhere air bubbles are mixed in the refrigerant in a subcooledliquid-phase state.

On the contrary, in order to allow the refrigerant flowing from therefrigerant inlet port 70 c into the swirling space 70 d to flow towardthe minimum passage area part 70 b so as not to block the flow of theliquid-phase refrigerant circulating around the gas column, as isapparent from FIG. 11, it is desirable that the refrigerant may mergeinto a flow from the outer peripheral side toward the minimum passagearea part 70 b side, of the refrigerant flow of the liquid-phaserefrigerant staying and circulating around the gas column.

What is claimed is:
 1. An ejector comprising: a swirling space formationmember having a swirling space in which a fluid is swirled; a nozzlethat depressurizes and ejects the fluid flowing out of the swirlingspace; and a body including a fluid suction port that draws a fluid dueto a suction action of the ejected fluid at high speed which is ejectedfrom the nozzle, and a pressure increase part that mixes the ejectedfluid with the suction fluid drawn from the fluid suction port andincreases a pressure of the mixed fluid, wherein the swirling spaceincludes an upstream swirling space in which the fluid flowing from anexternal is swirled, and a downstream swirling space that introduces thefluid flowing out of the upstream swirling space into the nozzle withkeeping the fluid swirling, the upstream swirling space and thedownstream swirling space have respective rotating body shapes in whichcenter axes are disposed coaxially with each other, the upstreamswirling space has an outlet part through which the fluid outflow to thedownstream swirling space, and the outlet part has an annular shapealong an outer peripheral shape of the upstream swirling space in across sectional surface perpendicular to the center axis, and thedownstream swirling space has a circular shape in a cross sectionalsurface perpendicular to the center axis.
 2. An ejector for a vaporcompression refrigeration cycle device, comprising: a body including arefrigerant inlet port, a swirling space in which a refrigerant flowingfrom the refrigerant inlet port is swirled, a depressurizing space inwhich the refrigerant flowing out of the swirling space isdepressurized, a suction passage that communicates with a downstreamside of the depressurizing space in a refrigerant flow and draws arefrigerant from an external, and a pressurizing space in which anejection refrigerant ejected from the depressurizing space is mixed witha suction refrigerant drawn from the suction passage; and a passageformation member that includes at least a portion disposed inside thedepressurizing space, and a portion disposed inside the pressurizingspace, the passage formation member having a conical shape whichincreases in cross-sectional area in a direction away from thedepressurizing space, wherein a refrigerant passage provided between aninner peripheral surface of the body defining the depressurizing spaceand an outer peripheral surface of the passage formation member is anozzle passage functioning as a nozzle that depressurizes and ejects therefrigerant flowing out of the swirling space, a refrigerant passageprovided between an inner peripheral surface of the body defining thepressurizing space and an outer peripheral surface of the passageformation member is a diffuser passage functioning as a diffuser thatmixes and pressurizes the ejection refrigerant and the suctionrefrigerant, the swirling space includes an upstream swirling space inwhich the refrigerant flowing from an external is swirled, and adownstream swirling space in which the refrigerant flowing out of theupstream swirling space is introduced into the nozzle passage withswirling, the upstream swirling space and the downstream swirling spacehave respective rotating body shapes in which center axes are disposedcoaxially with each other, the upstream swirling space has an outletpart through which the refrigerant outflow to the downstream swirlingspace, and the outlet part has an annular shape along an outerperipheral shape of the upstream swirling space in a cross sectionalsurface perpendicular to the center axis, and the downstream swirlingspace has a circular shape in a cross sectional surface perpendicular tothe center axis.
 3. The ejector according to claim 1, further comprisinga swirling promotion member that swirls the refrigerant in the upstreamswirling space around the center axis, wherein the swirling promotionmember includes a flow regulating plate, and the refrigerant adjacent toa center axis of the upstream swirling space flows radially outwardalong the flow regulating plate.
 4. The ejector according to claim 1,wherein the upstream swirling space has an annular shape in a crosssectional surface perpendicular to the center axis, and the upstreamswirling space is configured to allow the refrigerant having a velocitycomponent in a direction of swirling around the center axis of theupstream swirling space to flow into the upstream swirling space.
 5. Theejector according to claim 2, further comprising a swirling promotionmember that swirls the refrigerant in the upstream swirling space aroundthe center axis, wherein the swirling promotion member includes a flowregulating plate, and the refrigerant adjacent to a center axis of theupstream swirling space flows radially outward along the flow regulatingplate.
 6. The ejector according to claim 2, wherein the upstreamswirling space has an annular shape in a cross sectional surfaceperpendicular to the center axis, and the upstream swirling space isconfigured to allow the refrigerant having a velocity component in adirection of swirling around the center axis of the upstream swirlingspace to flow into the upstream swirling space.